The Collaborative International Dictionary

mains \mains\ (m[=a]nz), n. [Scot. See Manse.]
The farm attached to a mansion house; a manse. [Scot. or
Brit. dial.]

mains

mains \mains\ (m[=a]nz), n. (Electricity)
The source of electrical power in a building; the wiring
system of a building.

Wiktionary

mains

n. 1 (plural of main English)Category:English plurals 2 (context chiefly British English) The domestic electrical power supply. 3 The pipes of a centralized water supply that transport the water to individual buildings. 4 (context Scotland English) The farm attached to a mansion house.

The word Mains in Scotland normally refers to the main buildings of a farm. This may include the farmhouse, farm buildings such as a byre,dairy, and workers' cottages. It is pseudo-plural, actually being a Lowland Scots corruption of the Frenchdemesne, and so is never used in the form "Main" (except occasionally in the tautological "Main farm", although this usage is not traditional).

The mains was usually the principal farm on an estate, or at least the one with the most fertile ground. The rough equivalent in England would be a 'home farm' (or perhaps 'manor farm', but not a 'manor' or 'manor house'). The Laird's house - if there was one - may have been nearby or some distance away, but is not usually considered part of the mains. Many mains remain as working farms, while others have been converted to residential accommodation. Sometimes the buildings and/or farm have disappeared altogether and only the name of the location survives.

The word Mains occurs frequently in Scottish placenames, most noticeably in the north east and east coast regions, extending down into East Lothian if not even Berwickshire native knowledge. The usual form is "Mains of X", without the definite article "the", for example, "Mains of Hallhead". However, the best known example of its use in a Scottish placename is Davidson's Mains, now a suburb of Edinburgh, which does not follow this form. Indeed, south of the M8, Mains almost invariably take the form "X Mains", as in "Mordington Mains". The Shorter Oxford English Dictionary notes the same word/corruption/usage to have occurred in Northern England, and farm names of the form "X Mains" can also be found in northern Northumberland. In some cases, new owners have renamed various "mains" to "manor" in ignorance of the distinction in Scotland. The media occasionally uses the tautology, "Mains of X farm". Locally, it will be referred to as "the mains".

The word Mains is also a family name and a sept of the Scottish clan Gunn.

The connection of the laterals with the mains, the laying of the larger sizes of tiles so as to form a close joint, the wedging of these larger tiles firmly into their places, and the trimming which is necessary in going around sharp curves, and in putting in the shorter pieces which are needed to fill out the exact length of the drain, demand more skill and judgment than are often found in the common ditcher.

On very even land, where the whole surface, for hundreds of acres, slopes gradually in one or two directions, the outlay for mains need not be more than two per cent.

On less regular ground, the cost of mains will often be considerably more than two per cent.

Stroop tried to flush them out by flooding the mains but the Jews managed to stop the flow of water.

Two twenty-four-inch cooling mains, now empty, used to bring water up from a reservoir back in the bunker farm to cool the main steam condensers.